qquickmaterialplaceholdertext.cpp

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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "qquickmaterialplaceholdertext_p.h"
 
#include <QtCore/qpropertyanimation.h>
#include <QtCore/qparallelanimationgroup.h>
#include <QtGui/qpainter.h>
#include <QtGui/qpainterpath.h>
#include <QtQml/qqmlinfo.h>
#include <QtQuickTemplates2/private/qquicktheme_p.h>
#include <QtQuickTemplates2/private/qquicktextarea_p.h>
#include <QtQuickTemplates2/private/qquicktextfield_p.h>
 
QT_BEGIN_NAMESPACE
 
static const qreal floatingScale = 0.8;
Q_GLOBAL_STATIC(QEasingCurve, animationEasingCurve, QEasingCurve::OutSine);
 
/*
    This class makes it easier to animate the various placeholder text changes
    for each type of text container (filled, outlined).
 
    By doing animations in C++, we avoid having a bunch of states, transitions,
    and animations (which are all QObjects) declared in QML, even if that text
    control never gets focus and hence never needs them.
*/
 
QQuickMaterialPlaceholderText::QQuickMaterialPlaceholderText(QQuickItem *parent)
    : QQuickPlaceholderText(parent)
{
    // Ensure that scaling happens on the left side, at the vertical center.
    setTransformOrigin(QQuickItem::Left);
}
 
bool QQuickMaterialPlaceholderText::isFilled() const
{
    return m_filled;
}
 
void QQuickMaterialPlaceholderText::setFilled(bool filled)
{
    if (filled == m_filled)
        return;
 
    m_filled = filled;
    update();
    void filledChanged();
}
 
bool QQuickMaterialPlaceholderText::controlHasActiveFocus() const
{
    return m_controlHasActiveFocus;
}
 
void QQuickMaterialPlaceholderText::setControlHasActiveFocus(bool controlHasActiveFocus)
{
    if (m_controlHasActiveFocus == controlHasActiveFocus)
        return;
 
    m_controlHasActiveFocus = controlHasActiveFocus;
    if (m_controlHasActiveFocus)
        controlGotActiveFocus();
    else
        controlLostActiveFocus();
    emit controlHasActiveFocusChanged();
}
 
bool QQuickMaterialPlaceholderText::controlHasText() const
{
    return m_controlHasText;
}
 
void QQuickMaterialPlaceholderText::setControlHasText(bool controlHasText)
{
    if (m_controlHasText == controlHasText)
        return;
 
    m_controlHasText = controlHasText;
    maybeSetFocusAnimationProgress();
    emit controlHasTextChanged();
}
 
/*
    Placeholder text of outlined text fields should float when:
    - There is placeholder text, and
      - The control has active focus, or
      - The control has text
*/
bool QQuickMaterialPlaceholderText::shouldFloat() const
{
    const bool controlHasActiveFocusOrText = m_controlHasActiveFocus || m_controlHasText;
    return m_filled
        ? controlHasActiveFocusOrText
        : !text().isEmpty() && controlHasActiveFocusOrText;
}
 
bool QQuickMaterialPlaceholderText::shouldAnimate() const
{
    return m_filled
        ? !m_controlHasText
        : !m_controlHasText && !text().isEmpty();
}
 
void QQuickMaterialPlaceholderText::updateY()
{
    setY(shouldFloat() ? floatingTargetY() : normalTargetY());
}
 
qreal controlTopInset(QQuickItem *textControl)
{
    if (const auto textArea = qobject_cast<QQuickTextArea *>(textControl))
        return textArea->topInset();
 
    if (const auto textField = qobject_cast<QQuickTextField *>(textControl))
        return textField->topInset();
 
    return 0;
}
 
qreal QQuickMaterialPlaceholderText::normalTargetY() const
{
    auto *textArea = qobject_cast<QQuickTextArea *>(textControl());
    if (textArea && m_controlHeight >= textArea->implicitHeight()) {
        // TextArea can be multiple lines in height, and we want the
        // placeholder text to sit in the middle of its default-height
        // (one-line) if its explicit height is greater than or equal to its
        // implicit height - i.e. if it has room for it. If it doesn't have
        // room, just do what TextField does.
        // We should also account for any topInset the user might have specified,
        // which is useful to ensure that the text doesn't get clipped.
        return ((m_controlImplicitBackgroundHeight - m_largestHeight) / 2.0)
            + controlTopInset(textControl());
    }
 
    // When the placeholder text shouldn't float, it should sit in the middle of the TextField.
    return (m_controlHeight - height()) / 2.0;
}
 
qreal QQuickMaterialPlaceholderText::floatingTargetY() const
{
    // For filled text fields, the placeholder text sits just above
    // the text when floating.
    if (m_filled)
        return m_verticalPadding;
 
    // Outlined text fields have the placeaholder vertically centered
    // along the outline at the top.
    return (-m_largestHeight / 2.0) + controlTopInset(textControl());
}
 
int QQuickMaterialPlaceholderText::largestHeight() const
{
    return m_largestHeight;
}
 
qreal QQuickMaterialPlaceholderText::controlImplicitBackgroundHeight() const
{
    return m_controlImplicitBackgroundHeight;
}
 
void QQuickMaterialPlaceholderText::setControlImplicitBackgroundHeight(qreal controlImplicitBackgroundHeight)
{
    if (qFuzzyCompare(m_controlImplicitBackgroundHeight, controlImplicitBackgroundHeight))
        return;
 
    m_controlImplicitBackgroundHeight = controlImplicitBackgroundHeight;
    updateY();
    emit controlImplicitBackgroundHeightChanged();
}
 
qreal QQuickMaterialPlaceholderText::controlHeight() const
{
    return m_controlHeight;
}
 
void QQuickMaterialPlaceholderText::setControlHeight(qreal controlHeight)
{
    if (qFuzzyCompare(m_controlHeight, controlHeight))
        return;
 
    m_controlHeight = controlHeight;
    updateY();
}
 
qreal QQuickMaterialPlaceholderText::verticalPadding() const
{
    return m_verticalPadding;
}
 
void QQuickMaterialPlaceholderText::setVerticalPadding(qreal verticalPadding)
{
    if (qFuzzyCompare(m_verticalPadding, verticalPadding))
        return;
 
    m_verticalPadding = verticalPadding;
    emit verticalPaddingChanged();
}
 
void QQuickMaterialPlaceholderText::controlGotActiveFocus()
{
    if (m_focusOutAnimation)
        m_focusOutAnimation->stop();
 
    Q_ASSERT(!m_focusInAnimation);
    if (shouldAnimate()) {
        m_focusInAnimation = new QParallelAnimationGroup(this);
 
        QPropertyAnimation *yAnimation = new QPropertyAnimation(this, "y", this);
        yAnimation->setDuration(300);
        yAnimation->setStartValue(y());
        yAnimation->setEndValue(floatingTargetY());
        yAnimation->setEasingCurve(*animationEasingCurve);
        m_focusInAnimation->addAnimation(yAnimation);
 
        auto *scaleAnimation = new QPropertyAnimation(this, "scale", this);
        scaleAnimation->setDuration(300);
        scaleAnimation->setStartValue(1);
        scaleAnimation->setEndValue(floatingScale);
        yAnimation->setEasingCurve(*animationEasingCurve);
        m_focusInAnimation->addAnimation(scaleAnimation);
 
        m_focusInAnimation->start(QAbstractAnimation::DeleteWhenStopped);
    } else {
        updateY();
    }
}
 
void QQuickMaterialPlaceholderText::controlLostActiveFocus()
{
    Q_ASSERT(!m_focusOutAnimation);
    if (shouldAnimate()) {
        m_focusOutAnimation = new QParallelAnimationGroup(this);
 
        auto *yAnimation = new QPropertyAnimation(this, "y", this);
        yAnimation->setDuration(300);
        yAnimation->setStartValue(y());
        yAnimation->setEndValue(normalTargetY());
        yAnimation->setEasingCurve(*animationEasingCurve);
        m_focusOutAnimation->addAnimation(yAnimation);
 
        auto *scaleAnimation = new QPropertyAnimation(this, "scale", this);
        scaleAnimation->setDuration(300);
        scaleAnimation->setStartValue(floatingScale);
        scaleAnimation->setEndValue(1);
        yAnimation->setEasingCurve(*animationEasingCurve);
        m_focusOutAnimation->addAnimation(scaleAnimation);
 
        m_focusOutAnimation->start(QAbstractAnimation::DeleteWhenStopped);
    } else {
        updateY();
    }
}
 
void QQuickMaterialPlaceholderText::maybeSetFocusAnimationProgress()
{
    updateY();
    setScale(shouldFloat() ? floatingScale : 1.0);
}
 
void QQuickMaterialPlaceholderText::componentComplete()
{
    // We deliberately do not call QQuickPlaceholderText's implementation here,
    // as Material 3 placeholder text should always be left-aligned.
    QQuickText::componentComplete();
 
    if (!parentItem())
        qmlWarning(this) << "Expected parent item by component completion!";
 
    m_largestHeight = implicitHeight();
    if (m_largestHeight > 0) {
        emit largestHeightChanged();
    } else {
        qmlWarning(this) << "Expected implicitHeight of placeholder text" << text()
            << "to be greater than 0 by component completion!";
    }
 
    maybeSetFocusAnimationProgress();
}
 
QT_END_NAMESPACE